fuel gauge replacement question

looking to swap out old stewert warner gauges for autometer . for the fuel gauge they have a non linear and linear 73-10 ohm . so which one do i need . fuel sender and tank are oem replacements but are not nos, i read somewhere that factory original= non linear . factory replacement or aftermarket=linear / i know someone out in b-body land will know the answer . thanks

Original fuel sender is a guess non linear with a triangular shape rehostat, but replacement are with a symmetrical rehostat so I guess that becomes linear. Still these replacements are on the correct ohms rate ( 10-70 ) for the full and empty readings. So I guess that is what should be matched?

rad savoy said:

looking to swap out old stewert warner gauges for autometer . for the fuel gauge they have a non linear and linear 73-10 ohm . so which one do i need . fuel sender and tank are oem replacements but are not nos, i read somewhere that factory original= non linear . factory replacement or aftermarket=linear / i know someone out in b-body land will know the answer . thanks

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Curious as to the outcome of this @rad savoy

I settled for classic ind. sending unit mf 459 and autometer fuel gauge 3315 and somehow everything works together. / classic ind, said their fuel sender was made to factory spec. so i figured it as a non linear so i matched it with a non linear autometer fuel gauge - 500 miles later and everything is still working .

rad savoy said:

I settled for classic ind. sending unit mf 459 and autometer fuel gauge 3315 and somehow everything works together. / classic ind, said their fuel sender was made to factory spec. so i figured it as a non linear so i matched it with a non linear autometer fuel gauge - 500 miles later and everything is still working .

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Thanks for the update. I installed a Spectra Premium FG94A and have done all the usual stuff with grounds etc, and it just won't read accurately on the stock dash gauge. It could be the gauge as the old stock sender was not accurate by a mile either, or just the linear/non-linear issue.

The FG94A says it has a "Curved rheostat design for an accurate and continuous reading", so most likely linear based on the post by @Nacho-RT74 and looks different from the MF459 from Classic that you have.

I have recently updated a few of my gauges to Autometer, so sounds like the 3319 will be the one for me.